I've cracked base moulding multiple times when nailing because of this recess caving in.

what's the purpose of it?

joecaption

03-04-2013 06:11 PM

Base only needs to make full contact at the top and bottom, by having that gap the piece can span any flaws on the wall or make up for any cupping in the base.
Your not suppost to be nailing in the middle of baseboard.
Use a finish nailer and it will be 10 times faster and no splits.

woodworkbykirk

03-04-2013 06:41 PM

exactly, its the same thing with door jamb stock and hardwood flooring

Maintenance 6

03-05-2013 02:17 PM

It's there so that if the piece decides it wants to cup, the edges won't pull away from the wall.